Organic acid of the diphenyl-methane series and a process of preparing the same



No Drawing.

Patented Apr. 18, 1933 uNIrEosTAfr-Es PATENT OFFICE v IVAN GUBELMANN,HENRY, J. w InANn,

AND or'ro STAL'LMANN, OF scum: MIL- WAUKEE, WISCONSIN, ASSIGNORS, BYMESNE ASSIGNMENTS, TO E. I. DU PONT DE NEMIOURS & COMPANY, A CORPORATIONOF DELAWARE ORGANIC ACID 0]? TH DIPHENTL-METHANE sEEIEs AND A PROCESS OFPREPARING THE SAME This invention relates to 3'-amino-4-hydroxy (alkoxy)benzyl ortho benzoic acids, the readily hydrolyzable nitrogensubstitution products thereof, as for example the acidyls and the ureaderivatives, and to the process of preparing the same.

It is an object of this invention to provide a method whereby theseproducts may be made technically available as they are valuable productsin themselves and more'particularly so when .used as the startingmaterial for the preparation of dyestufis.

Other and further important objects of this invention will becomeapparent from the following description and appended claims.

In a copending application executed of even date herewith, there isdescribed a method for the preparation of 2- and 3-aminobenzyl orthobenzoic acids. We have now found that the 3-amino.-l-hydroxy (or alkoxy)-benzyl ortho benzoic acids may be prepared in a similar manner-and onaccount of their chemical structure are well adapted for the preparationof other products and, in particular, dyestuffs. These new products areprepared from the corresponding amino ben zoyl benzoic acids by reducingthe latter according to known methods adapted for the reduction of otherbenzoyl benzoic acids. as for example, with aqueous ammonia and zincdust. The reaction is probably best ex pressed'by the follo-wingchemicalequation:

OR OR I COzH either directly from the amino benzyl'beiizoic V scribed"in connection with the amines.

Application filed July 2, 1928. Serial No. 290,028.

acid derivatives by methods adapted to prepare similar derivatives ofaniline homologues or the acidyl derivative of the amino ben'zoylbenzoic acid derivative maybe reduced with zinc as in the case oftheunsubstituted' nitrogen amino ,body and isolated dirgctly as theacidyl amino benzyl benzoic ac1 Such derivatives as urea,benzyliden'e'and the like, may be prepared from the amino benzyl orthobenzoic acids by known methods adapted to prepare these derivatives fromother amines.

3-aminol-hydroxy (alkoxy) benzyl ortho benzoic acids are, in general,white or cream colored solids depending upon their purity. WVhen pure,they are practically white. They are soluble in dilute caustic soda,sodium carbonate, ammonia and the like, but are practically insoluble inwater. The addition of acids such as hydrochloric, sulfuric'and the liketo a water suspension transforms them into the corresponding salts,which at first dissolve to some extent, especially in a heated solutionand may then be precipitated by adding more acid and cooling. As thusobtained the products are in the form of their hydrochloridesor'sulfates, respectively. Upon treatment with concentrated sulfuricacid at an elevated temperature, 3 -amino-l'-methoxy benzyl orthobenzoic acid at first dissolves with a yellow color y. and then becomesgreenish and the solution will be found to contain the amino-anthrone.

This upon suitable treatment with oxidizing The acidyl derivatives arein general white crystalline substances. Concentrated sulfuric acidreacts upon them at an elevated temperature in a similar manner to thatIdlee anthrones can be-oxidized by suitable oxidizing agents to thecorresponding anthraquim one derivatives. ''The acidyl derivatives ofamino benzyl ortho benzoic acid may be saponified to the mothersubstances, namely the amino benzyl benzoic acids.

, Without limiting our invention to a'ny particular procedure, thefollowing examples in which parts by weight are given, will serve toillustrate our method in its preferred form.

Emample 1 A mixture containing 2000 parts of water, 1600 parts ofconcentrated ammonia, parts of copper sulfate (crystals), 271 parts of3-amino-4-methoxy ortho benzoyl benzoic acid and 500 parts of zinc dustis heated to 70 to 80 C. This temperature is maintained with agitationfor about fifteen hours. The zinc residues are then filtered from thereaction mass and to the filtrate are added about 200 parts of sodiumcarbonate. The ammonia is now distilled off and the residual liquoragain filtered to remove further insoluble residues. The filtrate ischarged into a small amount of ice to which about 100 parts of aceticacid have been added. The product separates and is filtered off. After arecrystallization from benzene, the product, 3,- amino--4cmethoxy benzylortho benzoic acid,- melts at 1481t9 C.

3-amino-4.--ethoXy benzyl ortho benzoic acid may be prepared in asimilar manner. 3-amino-4-ethoxy benzyl ortho benzoic acid melts at 137to 138 C.

Example 2 A mixture containing 257 parts of 3 amino- F-hydroxy orthobenzoyl benzoic acid, 1300 parts of ammonia (27%), 1800 parts of waterand parts of copper sulfate crystals, 500 parts of zinc dust is agitatedat to C. for 14 to 16 hours. The zinc residues are filtered and to thefiltrate are added 200 parts of sodium carbonate. The ammonia is nowdistilled OK. The residual liquor is then filtered from further residuesand the filtrate run into diluted sulfuric acid. The acidity of thissolution is then adjusted I by the further addition of sulfuric acid, if

necessary, to a point where it shows a strong acidity on Congo redpaper. The sulfate of 3-amino-4;-hydroxy benzyl ortho benzoic acidseparates. This crude product is filtered off and may be purified bydissolving it in hot 2% sulfuric acid and filtering hot from a smallamount of dark colored impurities with the aid of some filtercell. 7 Oncooling, the neutral sulfate of 3-aminolhydroXy benzyl ortho benzoicacid crystallizes out in small white needles forming star shapedaggregates.

By way of illustration the following example is given for thepreparation of 3- acetyl amino-4-meth0xy benzyl benzoic acid:

3'-amino-4-methoxy benzyl ortho benzoic acid is dissolved in glacialacetic acid and heated up after the addition of a small amount of aceticanhydride. Upon cooling and diluting with water, the acetyl derivativeis obtained in the form of white crystals; Upon recrystallizing thecrude body from diluted acetic acid, the 3-acetyl amino-4"- methpiiybenzyl ortho benzoic acid melts at 155 We are aware that numerousdetails of the process may be varied through a wide range withoutdeparting from the principles of this invention, and we, therefore, donot purpose limiting the patent granted hereon otherwise thannecessitated by the prior art.

We claim as our invention: 1. The process of preparing compounds of thegeneral formula:

in which R represents a hydrogen or an alkyl group, and R and R areH-atoms or readily hydrolyzable substituents which comprises reducingthe corresponding benzoyl compounds.

2. The process of preparing compounds of the general formula:

in'which It represents a hydrogen or an alkyl group, and, R and R areH-atoms or readily hydrolyzable substituents which comprises reducing.the corresponding benzoyl compounds with zinc in an ammoniacal solutionin the presence of copper salts.

' '3. As new articles of manufacture, 3- amino-4-oxy benzyl orthobenzoic acids of the following general formula:

OOOH

in which; R is an H-atom or an alkyl group, and R and R are H-atoms orreadily hydrolyzable substituents. V

4. As a new article of manufacture,-3'-amino-4-methoxy-benzyl-ortho-benzoic acid.

ioo

5. As new articles of manufacture, com pounds having the followingprobable general formula:

in WhichR and R are H atoms or acidyl groups.

6. The process of preparing a 3-amino-4'- alkoxy-benzyl-ortho-benzoicacid which is a member of the group consisting of the primary 3 amino-4alkoxy-benzyl-ortho-benzoic acids and those N-substitution derivativesthereof which contain a readily hydrolyzable substituent in the N-atom,which comprises reducing the corresponding3-amino-4:'-alkoxy-benzoyl-ortho-benzoic acid.

7. The process of preparing a 3-amino-4- alkoxy-benzyl-ortho-benzoicacid which is a member of the group consisting of the primary 3 amino-4alkoxy-benzyl-ortho-benzoic acids andthoseN-substitutionderivativesthereof which contain a readily hydrolyzable substituent in the N-atom,which comprises reducing the corresponding3-amino-4-alkoxy-benzoyLortho-benzoic acid with zinc in ammoniacalsolution in the presence of copper sulfate.

8. As new articles of manufacture, 3'- amino-F-alkoxy-benzyl-ortho-benzoic acids which are members of the groupconsisting of the primary 3-amino-4-alkoxy-benzyl ortho-benzoic acidsand those N-substitution derivatives thereof which contain a readilyhydrolyzable substituent in the N-atom.

9. A process of preparing a 3'-amino-4- alkoxy-benzyl-ortho-benzoic acidwhich is a member of the group consisting of the primary 3 amino-4calkoxy-benzyl-ortho-benzoic acids and those N-substitution derivativesthereof which contain a readily hydrolyzable substituent in the N -atom,which comprises reducing the corresponding3'-amino-4'-alkoxy-benzoyl-ortho-benzoic acids with zinc in an alkalinesolution in the presence of a copper salt and at a temperature of 70 to80 C.

In testimony whereof we have hereunto subscribed our names atCarrollville, Milwaukee County, Wis.

IVAN GUBELMANN.

. HENRY J. WEILAND.

o'rro STALLMANN.

